ES2689397T3 - Metal container - Google Patents

Abstract

A container comprising: a container body (1) of metal, the body comprising a base (4) and a generally cylindrical side wall (3), wherein the upper edge of the cylindrical side wall is rolled up to form a lip hollow annular ring (5) surrounding the upper open end of the container body, and in which a discontinuity is formed in the form of one or more depressions (6) and/or one or more projections (6) on the annular lip in a respective circumferential point or circumferential points; and a releasable closure (2) formed with an end wall (7) and a dependent skirt (8), and characterized in that it has an annular layer (9) of sealing material provided inside the end wall adjacent to the skirt, being sealing material such that it is cured before the filling process but softens during the filling and capping process with steam in a headspace above a food product; wherein, when the closure is pressed onto the container body, the annular lip engages the annular layer of softened sealing material and part of that sealing material extends into the one or more depressions and/or around one or more protrusions; and a partial vacuum within the container body, so that the closure is held in the container body by virtue of the partial vacuum formed in the container body during production of the filled container.

Description

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DESCRIPTION

Metal container Technical field

The invention relates to a metal container body for use with a releasable closure containing an annular layer of sealing compound.

Prior art

A container is known that comprises a metal can body having a generally cylindrical side wall with a top edge wound on top to form an annular cord that surrounds the upper open end of the body for use with a sealed lid closure that is sealed. to the can body and is held in position only by a vacuum that is formed in the upper space above the product in the container during processing. The lid is formed with a vacuum release means comprising a small opening in the final wall of the closure that is normally closed by a detachable plastic insert or a peelable patch. After releasing the vacuum, the closure of the container body is removed. Metal containers formed with a thread passage for connecting to a closure are also known, but the formation of the thread passage in the neck of the container is very difficult to achieve and tends to damage the internal linings of the container that protect the metal of the container of the container. container versus the contents of the container.

Also known are the containers in which a metal releasable lid closure that contains a layer of sealing compound is embedded in a glass container body. Traditionally, the lid is screwed onto the body so that the upper surface of the neck of the container is sealed against the layer of sealing compound. Filling rates for such containers are generally up to about 500 containers per minute.

Due to the time required to fit a screw closure during production, a modified arrangement has been developed in which a seal with molded sealing compound is formed on the outside of the final wall of the closure and inside the side wall or skirt of the closure. This type of closure can be pressurized on a threaded container during the production of a full container. The filling rates of said containers can be up to 1,000 containers per minute. The threads of the body screws are introduced into the sealing compound to form at least a partial thread therein so that, when the container is opened, the relative rotation of the closure and the body of the container will break the seal and allow remove the closure. This arrangement is useful for certain food products when a partial vacuum is maintained in the container after filling and closing. During the container filling procedure, steam is injected into the open container in the upper space over the hot food product that has been measured in the container. Next, the closure is pressed on the container and, as the steam condenses, a partial vacuum is formed in the container above the upper space that acts to hold the closure firmly in place on the body of the container. In the fully cooled full container, the typical vacuum in the container is approximately 0.3 bar. This partial vacuum must be vented to allow the lid to be removed.

Document US2011 / 278255 discloses a cover for an ear-type closure. EP2431297 discloses a process for producing a container full of food and sealing. Document US3181719 discloses a metal pressure seal and a container body provided with depressions or cams on its edge.

Disclosure of the invention

The invention provides an arrangement in which neither the container nor the closure need to be provided with a screw thread or any other means of mechanical coupling to make a seal between the closure and the body of the container. The closure is simply pushed down on the full container to form the seal. In the arrangement of the present invention, the closure is maintained on the body of the container by virtue of the partial vacuum formed in the body of the container during the production of the full container. The container body is provided with a discontinuity in its annular sealing surface that causes the seal to break and the interior of the body to be ventilated when the lid closure is rotated from the original closed position so that the seal is released. lid closure.

According to the invention, a container is provided comprising a metal container body; the body comprising a base and a generally cylindrical side wall; wherein the upper edge of the cylindrical side wall is wound to form a hollow annular cord that surrounds the open upper end of the container body; and in which a discontinuity is formed in the cord in the form of one or more depressions and / or one or more projections at a circumferential point or respective circumferential points. The container further comprises a releasable closure formed with a final wall and a dependent skirt. The closure has an annular layer of sealing material provided inside the final wall adjacent to the skirt, the sealing material being such that it is cured before the filling procedure but is softened during the filling and steam capping process in a upper space over a food product; wherein, when the closure is pressed on the body of the container, the annular cord is coupled to the annular layer of softened sealing material and part of that sealing material extends into the one or more depressions and / or around of one or more outgoing. There is a void

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partial inside the body of the container, so that the closure is maintained in the body of the container by virtue of the partial vacuum formed in the body of the container during the production of the full container.

The invention provides several advantages. The closure is simply removed from the body by twisting and there is no need to provide a vacuum release device on the final wall of the closure.

It is not necessary to provide a screw thread in the neck of the container. This greatly simplifies the fabrication of the container body and saves material, since a shorter neck can be provided.

Having only one annular layer of sealing compound on the final wall of the lid closure means that the sealing compound does not need to be molded but can be formed by gravity. This uses less compound, greatly simplifies manufacturing and eliminates scrap generated in the compound molding process.

Since the lid closure does not require the lugs to be attached to a thread, a very small radial space can be provided between the closure skirt and the neck of the container body. This reduces the risk of entry of foreign bodies, insects, etc. and also increases resistance to accidental damage.

The absence of threads in the lid means that it can have a reduced height, which saves material.

The torque required to open a container made in accordance with the invention is considerably smaller than that typically required to open a threaded container. For example, the opening torque for a 51 mm closure has been reduced from approximately 3.4 Nm to only approximately 1.0 Nm. The reduction in the opening torque allows the use of less lubricants in the compound. These lubricants are one of the main causes of migration to food during processing. Therefore, the new design also has benefits for food safety.

Brief description of the drawings

The embodiments of the invention are described below with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a container body;

Figure 2 is a perspective view of a container body and a closure;

Figure 3 is an enlarged partial view of an upper part of the container body;

Figure 4 is an additional enlarged plan view of part of the edge of the container body;

Figure 5 is a cross-sectional view through part of the upper part of the container body;

Figure 6 is a view similar to Figure 5 taken through the notch in the edge;

Figure 7 is an exploded view of the top of the container and the closure;

Figure 8 is a perspective view of the top of the container and the closure when mounted on the

same;

Figure 9a is a cross-sectional view through part of the upper part of the container and the closure taken at point A in Figure 7;

Figure 9b is a cross-sectional view through part of the upper part of the container and the closure taken at point B in Figure 7;

Figure 9c is a cross-sectional view through part of the upper part of the container and the closure taken at point C in Figure 7;

Figure 10 is a cross-sectional view through part of the upper part of the container and the closure taken at point B in Figure 7 after the closure has turned counterclockwise; and Figure 11 is a cross-sectional view through part of the upper part of the container and the closure taken at point C in Figure 7 after the closure has rotated counterclockwise.

Mode (s) for carrying out the invention

The figures show a container body 1 and a lid closure 2, both made of metal. The body 1 of the container has a side wall 3 made of a metal sheet that is formed in a cylinder with the ends of the sheet superimposed slightly and welded together along a seam. This type of manufacturing is well known. The bottom bottom wall 4 of the container is attached to the cylindrical side wall.

The upper end of the side wall 3 has been rolled out to rotate at the cut end of the side wall. The coiled upper part of the end of the side wall forms a hollow annular lip or flange 5 that surrounds the open upper end of the container body to form the edge of the container, whose upper surface provides an annular sealing surface. In an alternative (not shown), the upper part of the side wall can be rolled inward to form the annular lip. For example, a 73 mm diameter welded tin body is made of 0.18 mm thick tinplate steel and has an upper lip or flange 5 with a diameter of approximately 1.5 to 2 mm.

As shown, a single notch 6 is formed in the annular lip 5 at a circumferential point. The notch is formed as a small dent or recess generally oriented radially outward. The depth of the notch is approximately 0.4 mm, about a quarter of the diameter of the lip and has an extension

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circumferential approximately 4 to 5 mm, about twice the diameter of the lip.

The number and depth of the notches can be varied in order to provide a relatively easy rotation of the closure and to ventilate in 5 seconds. Ideally, ventilation should be completed in 1 to 2 seconds. This can be achieved with a single notch that has a depth of approximately 0.4 mm or two or three notches that have a depth of approximately 0.2 mm.

The notch or notches can be formed on the lip, after curling the upper end of the side wall to form the lip, pushing the lip into a suitable die.

In an alternative embodiment (not shown), the discontinuity in the lip is formed by one or more protrusions in the lip. These projections can be provided by squeezing or otherwise working the lip formed in one or more circumferential locations.

The lid closure 2 is formed with a final wall 7 and a dependent skirt 8. An annular layer 9 of sealing material is provided inside the final wall adjacent to the skirt. When the closure 2 is pressed on the body of the container during processing, the annular sealing surface on the annular lip is coupled to the annular layer 9 of the sealing material and part of that material extends to the notch and fills at least partially, the notch as seen in figure 9b. If the lip is formed by one or more protrusions, the sealing material will extend at least partially around the protrusions.

The closure can be formed with a plurality of lobes at the bottom of the skirt. These lobes form tweezers that provide a snap fit with the lip of the body to help re-adjust the closure after opening. However, they do not play any role in the formation of a seal between the closure and the body of the container and must move upward beyond the lip once the seal has been broken. The closure is preferably made of tin steel.

The final wall has a central pop-up panel known as "vacuum button" 10 which is normally held concave by partial vacuum in the closed container. The button emerges in a convex way to warn that the vacuum has been vented and, therefore, the seal has been broken. The closure must be made of steel instead of aluminum to provide this feature.

The sealing compound is a PVC plastisol and is applied to the closure through a nozzle and allowed to settle by gravity to form a generally uniform annular layer. It is cured before the filling procedure but will be softened during the filling and steam capping process in the upper space over the food product so that it can flow into the groove 6 and set around the annular sealing surface 4 and within the notch

Vapor condensation causes a partial vacuum of approximately 0.3 bar in the upper space that forms a seal between the body and the closure and keeps the closure firmly on the body.

After capping, the filled container is normally processed according to the required food preservation conditions, for example, products with high sugar, acid or salt content may only have to be filled or hot pasteurized at 85 to 100 ° C while meat products that do not have natural preservatives require a complete sterilization procedure at 121 to 130 ° C to preserve the food product. Specific types of compounds have been developed to meet the different processing conditions, for example, a blown compound is typically used for pasteurized products, since this has trapped gas pockets within the sealing layer that make the compound flexible for adapt to the sealing surface at relatively low temperatures. For sterilized products, less or no blowing agent can be used to form a stiffer sealing layer that is more elastic and suitable for higher temperature processing. The inventors have discovered that the most rigid non-blown materials are particularly suitable for creating a ventilation characteristic. In this case, the compound best retains the shape memory of the notch after processing and forms a stable ventilation path when the lid is first rotated as explained below.

Other types of sealing gasket materials may also be used, such as non-flowing PVC materials, compression molded TPE materials or separate elastomeric coating materials.

The body 1 of the container is formed with an annular protuberance 15 under the annular lip 5 to protect the lower edge of the closing skirt against lateral impact during the handling of the can. This also provides circular resistance for the upper portion of the can, which prevents it from adopting an oval shape due to the impact on the closure.

The can is specifically designed to have a high axial load capacity to allow palletizing after closing and processing. Normally loads of more than 1.5 kN are achieved through the use of shallow angular profiles within the side wall, where changes in geometry are not more than 30 degrees from the vertical.

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High resistance of the packing is required to resist the processing and distribution of the processed package, which will normally have a vacuum of approximately 0.3 bar, so the specification of the container will be at least 0.5 bar. Paneling resistance is provided by lip formation (multiple circumferential lips) or cylinder shaping (large spherical profile).

The opening of the sealed container is treated with reference to Figures 7 to 11. Before opening, a partial vacuum in the container is the only mechanism that holds the closure 2 in the container body. The opening procedure requires that the seal between the closure and the body of the container be broken in such a way that the partial vacuum is vented and the closure is released.

In Figure 7, positions A, B and C are indicated. The opening procedure requires the rotation of the lid closure in relation to the body of the container and it will be natural for the user to rotate the closure counterclockwise on the body of the container. In this case, the part of the closure originally in position A will move to position B and the part of the closure originally in position B (the position of the notch) will move to position C.

Figures 9a, 9b and 9c show cross-sectional views through the container and the closure in positions A, B and C before opening. It can be seen that the upper surface of the lip 5 forms a recess in the layer 9 of sealing material and that this recess is narrower in the position B in which the sealing material extends into the notch. As the closure is turned counterclockwise, the narrow recess in position B forces the closure of the container elevation to break the seal between the closure and the container, as shown in Figure 11. At the same time, the wider recess formed in position A forms a ventilation path when turned to position B due to the slight elevation of the closure. This ventilation path is indicated by arrows in figure 10.

In the embodiment shown, only a single ventilation notch is provided because there is a load induced by each notch, so having only one reduces the total load. Second, the axial load necessary to lift the panel against vacuum is less if it is only on one side. Two or more notches may be provided but it is believed that the best solution is to have only one, since this reduces the torque required to open the container. However, there is a risk that a single notch will be perceived by the end user as a defect. This is likely to be somewhat mitigated if two or more notches are provided.

If the lip is formed with one or more protrusions instead of one or more depressions, the sealing material will extend, at least partially, around the protrusions and the mechanism that will occur during the opening of the container will be the same.

It will be understood that the closure cannot be adequately released from the container body after opening and release of the vacuum. This arrangement is appropriate for food products that should be consumed immediately once the container has been opened, although the closure can be replaced in the container and used as a cover, for example, when food is stored in the refrigerator.

Claims (10)

5 10 fifteen twenty 25 30 35 1. A container comprising: a body of the metal container (1), the body comprising a base (4) and a generally cylindrical side wall (3), in which the upper edge of the cylindrical side wall is wound to form a hollow annular lip (5) surrounding the upper open end of the container body, and in which a discontinuity is formed in the form of one or more depressions (6) and / or one or more projections (6) in the annular lip at a circumferential point or circumferential points respective; and a releasable closure (2) formed with a final wall (7) and a dependent skirt (8), and characterized in that it has an annular layer (9) of sealing material provided inside the final wall adjacent to the skirt, the sealing material being such that it is cured before the filling procedure but is softened during the filling and steam capping process in an upper space above a food product; wherein, when the closure is pressed on the body of the container, the annular lip is coupled to the annular layer of softened sealing material and part of that sealing material extends within the one or more depressions and / or around one or more outgoing; and a partial vacuum within the container body, so that the closure is maintained in the container body by virtue of the partial vacuum formed in the container body during the production of the filled container. 2. The container of claim 1, wherein the annular sealing material is formed of a solid material that takes a permanent assembly when cured and cooled. 3. The container of claim 1 or claim 2, wherein the body of the container is formed with an annular protrusion under the annular lip to protect the closure skirt from side impact. 4. The container of any of the preceding claims, wherein the diameter of the annular lip is approximately 1.5 to 2 mm. 5. The container of any of the preceding claims, wherein the discontinuity is formed as one or more notches in the lip. 6. The container of claim 5, wherein the depth of each notch is approximately 0.2 to 0.5 mm. 7. The container of any of the preceding claims, wherein the circumferential length of the notch is approximately twice the diameter of the annular lip. 8. The container of any of the preceding claims, wherein the side wall of the container is formed from a sheet of metal rolled in a cylinder and welded: and in which the base of the cylinder is attached to the side wall. 9. The container according to any of claims 1 to 8, wherein mechanical coupling means are not provided to make a seal between the closure and the body of the container. 10. The container according to any of the preceding claims, wherein the container has a profile in its cylindrical wall to provide at least 0.5 bar of operation of the packing.